The present invention relates generally to suspension systems. More specifically, the present invention relates to vehicle seat suspension systems.
Vehicle seat suspension systems are commonly used to increase rider comfort in vehicles. Low profile seats in automobiles typically include arrays of spring mechanisms for support, while high profile seats found in heavy trucks and buses offer room for more elaborate mechanisms.
Conventional seat suspension systems for high profile seats often include an air spring for providing load-bearing support and a shock absorber for providing damping support. Consider, for example, the conventional seat suspension system 100 illustrated in FIG. 1. The seat suspension system 100 includes a seat 110, a seat base 112 and a seat coupling 114 interposed between the seat 110 and the seat base 112. The seat coupling 114 may, for example, include a scissor support 115. An air spring 120 is interposed between the seat 110 and the seat base 112. The air spring 120 typically provides the primary load-bearing support for the seat 110, and thus is generally coupled to the seat 110 or seat coupling 114 at a position along the centerline 111 (or main load-bearing line) of the seat 110. Since the air spring 120 is generally flexible, it may be rigidly coupled at the lower end 122 and upper end 124 to the seat base 112 and the seat coupling 114 respectively.
The seat suspension system 100 also includes a shock absorber 130 for damping relative motions induced between the seat 110 and the seat base 112. The shock absorber 130 is typically coupled to the seat base 112 and seat coupling 114 at the lower shock end 132 and upper shock end 134 respectively. Since the air spring 120 typically occupies the space beneath the center of the seat 110, the shock absorber 130 is coupled to the seat 110 or seat coupling 114 at a position offset from the centerline 111 of the seat 110.
There are a number of disadvantages to the conventional seat suspension system 100, exemplified in FIG. 1, and other conventional seat suspension systems. One disadvantage is that since the shock absorber 130 is coupled to the seat coupling 114 at a position offset from the centerline 111 of the seat 110, the shock absorber 130 operates at a mechanical disadvantage. Thus, the shock absorber 130 is generally specified to provide more damping force than would be necessary if the shock absorber were more efficiently mounted. In addition, since the shock absorber 130 is providing damping force to the seat coupling 114 at a position offset from the centerline 111 of the seat 110, the damping force provided by the shock absorber 130 results in moments in the structure of the seat suspension system 100. The moments, in turn, induce twisting on the structure of the seat suspension system 100, leading to increased wear and reduced service life. The twisting, in turn, may also result in discomfort for the user of the seat suspension system 100.
Another disadvantage to the conventional seat suspension system 100 is that it is relatively expensive to manufacture. Two separate components, the air spring 120 and the shock absorber 130, govern the relative motion between the seat 110 and the seat base 130. Each of the two components, in turn, requires respective mounting hardware. Material supply lines must be managed for the air spring 120, shock absorber 130 and respective mounting hardware. The material supply lines may involve different suppliers. In addition, the relatively high part count complicates assembling the seat suspension system 100. Unnecessarily high part count typically corresponds to high production cost, reduced product reliability, increased production cycle time, and poorer overall product quality.
The need has long existed for an improved seat suspension system that provides increased user comfort, increased reliability, increased manufacturability, and reduced cost.